Casting is a technique used in the fields of steel and non-ferrous metal production. Continuous casting is known as one form of the casting technique. Continuous casting is a process including a step of withdrawing a cast rod formed in a mold in the vertical direction or the horizontal direction. A material is melted in a crucible, and the melt is poured into a pipe mold through a nozzle provided on the bottom of the crucible. In the mold, the material is continuously solidified and an obtained cast product is continuously withdrawn from the mold. Thus, a cast rod is obtained. In the case of horizontal continuous casting, it is also possible to drop a melt into a mold from a crucible or a tundish.
A mold is tapered to reduce frictional resistance acting on a cast rod when it is withdrawn and to prevent failure of withdrawal of the cast rod and breakage thereof. The mold is usually tapered, taking into account the volumetric shrinkage of a material such as steel during solidification, so that the width of the mold decreases in the withdrawal direction from the melt feeding side (see Patent Literatures 1 and 2).
Materials other than steel are also molded by casting in some cases. For example, silicon is not only added to metallic materials such as steel but also used for semiconductors, solar cells, etc. In particular, as methods for producing silicon for solar cells, attempts have been made to mold silicon by casting (see Patent Literatures 3 and 4).
The present inventors have proposed a method for obtaining a vapor-deposited film of silicon efficiently and at low cost by feeding silicon into a crucible using a silicon rod molded by casting (see Patent Literature 5).